Chronology

The very first step in grasping History is to understand chronology. ‘Chronology’ means the order in time in which events occurred.

There are several rules that have been developed over time to achieve this and they are outlined below. The terms and concepts outlined here can be used in your own historical writing to improve
your academic vocabulary.

Sequencing Time

The measurement of time is traditionally based around the birth of Jesus Christ.

For events that occurred before Jesus’ birth, type ‘BC’ (an abbreviation for ‘Before Christ’) after
the number.

For example: 48 BC.

For events that happened after Jesus’ birth, type ‘AD’ (an abbreviation for the Latin phrase anno domini, which means “Year of our Lord”)
before the number.

For example: AD 120.

For those who prefer a non-religious version, the following alternatives are placed after the number:

BCE (Before Common Era) = BC

For example: 48 BC is 48 BCE

CE (Common
Era) = AD

For example: AD 120 is 120 CE

Additional notes regarding dates:

If there isn’t a ‘BC’ or ‘AD’ next to a date, it is probably AD

Before the birth of Christ, the number of years counts down, but after that, the years count upwards

There is no year ‘0’: the year 1 BC is followed immediately by AD 1

‘BP’ after a number stands for ‘Before the Present’

‘Circa’ means ‘around about’ and is a small ‘c.’ before the year. For example: c. 50 BC

Division of Time

To talk about large sections of time, years are grouped together in the following way:

Decade = 10
years

Century = 100 years

Millennium = 1000 years

As a result, time can be split into centuries or millennia, as is demonstrated below:

Years

Century

Millennium

1000 -901 BC

10th century BC

1st millennium BC

900 – 801 BC

9th century BC

800 – 701 BC

8th century BC

700 – 601 BC

7th century BC

600 – 501 BC

6th century BC

500 – 401 BC

5th century BC

400 – 301 BC

4th century BC

300 – 201 BC

3rd century BC

200 – 101 BC

2nd century BC

100 – 1 BC

1st century BC

AD 1 - 100

1st century AD

1st millennium AD

AD 101- 200

2nd century AD

AD 201 – 300

3rd century AD

AD 301 – 400

4th century AD

AD 401 – 500

5th century AD

AD 501 – 600

6th century AD

AD 601 – 700

7th century AD

AD 701 – 800

8th century AD

AD 801 – 900

9th century AD

AD 901 – 1000

10th century AD

AD 1001 - 1100

11th century AD

2nd millennium AD

AD 1101- 1200

12th century AD

AD 1201 – 1300

13th century AD

AD 1301 – 1400

14th century AD

AD 1401 – 1500

15th century AD

AD 1501 – 1600

16th century AD

AD 1601 – 1700

17th century AD

AD 1701 – 1800

18th century AD

AD 1801 – 1900

19th century AD

AD 1901 – 2000

20th century AD

AD 2001 – Present Day

21st century AD

3rd millennium AD

Historical Periods

To make sense of the past, it is divided into larger blocks of time called ‘periods’. Each of these ‘periods’ can be broken down further into smaller times
called ‘ages’ and even into smaller times called ‘eras’.